The objective of this research is to isolate antineoplastic substances from a group of marine organisms which have been confirmed by the National Cancer Institute as active potential sources of antitumor substances by PS (lymphocytic leukemia) or KB (cell culture of human nasopharanx carcinoma) test systems. Isolation will be guided by activity testing provided by the National Cancer Institute. Structures of pure active compounds will be determined. The structure of other new compounds incidentally obtained in the course of isolating the active antitumor agents will be investigated to the extent possible.